Method and circuit for data transmission

ABSTRACT

The sampling rate of the optical and electrical signals provided by a DVD player according to standard IEC 61937 are converted in a first transcoder to the sampling rate of a multimedia network. The signals generated by the first transcoder with the sampling rate of the multimedia network are transmitted through a multimedia network line to a second transcoder, which based on the parameters contained in the signals received generates the signal originally generated by the DVD player and transmits it according to standard IEC 61937 to a DVD decoder. The technique is specifically suited for use in a motor vehicle and is distinguished by low technical complexity since without the transcoding by the two transcoders the encoded data stream at the output of the DVD player would have to be first decoded and then transmitted in multichannel mode as linear PCM data through a multimedia network line, for example, a MOST line. This approach, however, requires three to four times the bandwidth. In addition, the PCM data would have to be re-encoded for copyright reasons.

BACKGROUND OF THE INVENTION

[0001] The present invention relates to the field of signal transmissionand decoding systems, and in particular to apparatus and method fortransmitting data from a DVD player to a DVD decoder.

[0002] DVD players provide a digital output from which electrical oroptical signals may be picked up. An audio decoder such as a DolbyDigital, DTS, MPEG, or MLP decoder may be connected to the output of aDVD player. Unencoded pulse code modulation (PCM) stereo audio databased on the IEC 60958 standard, or encoded multichannel audio databased on the IEC 61937 standard, is sent to the decoder from the digitaloutput of a DVD player. In addition to the audio data, parametersettings (e.g., headers) for the decoder such as for example thesampling rate of the original data source may also be contained in thetransmitted data stream. The data stream to be transmitted isbiphase-coded and coupled to the sampling rate. The decoder (i.e., thedata sink) is thus able to synchronize itself and reconstruct theoriginal sampling rate of the data source, which for a DVD player, forexample, is 48 KHz.

[0003] A Media Oriented System Transport or Media Oriented SynchronousTransfer (MOST) is a multimedia network developed for use in a motorvehicle. A fundamental feature of a MOST network is the fact that theapplications layer is separate from the network layer. MOST networksalso work on the basis of biphase-coded data. Data are typicallytransmitted at a sampling rate of 44.1 KHz.

[0004] Additional information on MOST networks is disclosed in thepublication entitled “No Standard without Digitalization”,Automobil-Entwicklung, May 2000, pages 88-90, and in the publicationentitled “Media Oriented System Transport (MOST), Standard forMultimedia Networking in Motor Vehicles” VDI Berichte, no. 1415, 1998,pages 819-834.

[0005] A problem is that data from a data source such as a DVD player,has a first sample rate f₁, that is not compatible with a multimediatransmission medium that employs a second sample rate f₂, and acrosswhich data is transmitted from the data source to a data sink, such as aDVD decoder.

[0006] Therefore, there is a need for a technique for transmitting datafrom a data source such as a DVD player to a data sink such as a DVDdecoder, via a multimedia network line, such as a MOST network, at afrequency that differs from that of the data from the data source.

SUMMARY OF THE INVENTION

[0007] Briefly, according to an aspect of the invention, a signaltransmission and decoding system includes a data source that transmitsfirst encoded data over a first transmission medium. A first transcoderreceives the first encoded data via the first transmission medium, andtranscodes the first encoded data to provide transcoded encoded datathat is transmitted over a second transmission medium. A secondtranscoder that receives the transcoded encoded data via the secondtransmission medium, and transcodes the transcoded encoded data toprovide second encoded data that is transmitted over a thirdtransmission medium. A data sink that receives the second encoded datavia the third transmission medium, and decodes the second encoded datato provide decoded data.

[0008] In a preferred embodiment, the data source includes a DVD player,the data sink includes a DVD decoder, and the second transmission mediumcomprises a MOST bus.

[0009] According to another aspect of the invention, a method oftransmitting data from a DVD player to a DVD decoder includestransmitting encoded data from the DVD player over a first transmissionmedium, and receiving the encoded data and transcoding the receivedencoded data to provide transcoded encoded data. The transcoded encodeddata is transmitted over a second transmission medium, and then receivedand transcoded to provide received encoded DVD data. The receivedencoded DVD data is then transmitted over a third transmission medium tothe DVD decoder.

[0010] In one embodiment, the signals of standard IEC 61937 supplied bythe DVD player are transmitted to a first transcoder that analyzes thedata stream received from the DVD player and determines the samplingrate. The first transcoder adjusts the sampling rate to that of thestandard used by the multimedia network by changing the length of thepause packets contained in the data stream. If, for example, thesampling rate of the DVD player at 48 KHz is greater than the 44.1 KHzsampling rate required by the standard of the multimedia network, thefirst transcoder deletes a predetermined number of zeroes in the pausepackets. To achieve this, for example, a phase-locked loop is providedin the first transcoder that converts the frequency of the biphasesignal provided by the DVD player from 48 KHz to 44.1 KHz. The datastream generated by the first transcoder is transmitted through amultimedia network line to a second transcoder which, based on theparameters contained in the data stream received by the firsttranscoder, reproduces the data stream generated by the DVD player. Inone embodiment, transmission of data from the DVD player to the firsttranscoder and from the second transcoder to the DVD decoder isperformed according to standard IEC 61937.

[0011] In a data stream based on standard IEC 61937, unassigned bits arepresent which, in one embodiment of the invention are used to providecontrol commands. The unassigned bits indicate, for example, how manyzeroes must be deleted from the data stream or added to the data stream.

[0012] These and other objects, features and advantages of the presentinvention will become more apparent in light of the following detaileddescription of preferred embodiments thereof, as illustrated in theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWING

[0013] The FIGURE is a block diagram illustration of a signaltransmission and decoding system.

DETAILED DESCRIPTION OF THE INVENTION

[0014] The FIGURE is a block diagram illustration of a signaltransmission and decoding system 10. The system 10 includes a datasource 12 that provides a signal on a line 14 to a first transcoder 16.The first transcoder 16 provides a signal on a line 18 (e.g., amultimedia network line such as a MOST bus) to a second transcoder 20,which provides a signal on a line 22 to a data sink 24.

[0015] The present invention shall be discussed in the context of anembodiment wherein the data source is a DVD player, and the data sink isa DVD decoder. The DVD decoder 24 may, for example, be a Dolby Digitaldecoder, a dts decoder, an MPEG decoder, an MLP decoder, or anothermultichannel audio decoder. However, the invention is of course notlimited to systems wherein the data source is a DVD player, and the datasink is a DVD decoder.

[0016] The first transcoder 16 receives the signal on the line 14, andconverts the sampling rate of the received signal to the sampling ratecompatible with/required by the line 18. Depending on whether thesampling rate of the DVD player 12 is greater than or less than thesampling rate for the transmission of data over the multimedia network18, the first transcoder 16 removes zeroes from the pause packets oradds zeroes to them. Certain parameters are contained in the data streamthat the first transcoder 16 transfers through the multimedia network 18to the second transcoder 20. Using these parameters and the datareceived over the multimedia network 18, the second transcoder 20recreates the signal originally transmitted by the DVD player 12. Thesecond transcoder 20 transmits the recreated signal to the DVD decoder25 over the line 22, which may be configured and arranged according tostandard IEC 61937.

[0017] The signal transmission and decoding system 10 may be located ina motor vehicle. For example, the DVD player 12 may be connected, forexample, through a MOST network to the DVD decoder 24. That is, themultimedia network 18 may be configured and arranged for example as aMOST network. In one embodiment, the signal transmission and decodingsystem 10 may be employed in a motor vehicle, such as an automobile.

[0018] The present invention is distinguished from techniques whereinthe encoded data stream is decoded at the data source (e.g., the DVDplayer), and then transmitted in multichannel mode as linear PCM datathrough for example a MOST network. However, this technique requires abus bandwidth that is three to four times greater than the bus bandwidthrequired by the system of the present invention. In addition, the PCMdata would have to be re-encoded once again for copyright reasons sincedecoded Dolby or dts data may not be transmitted in an open system.Therefore, when compared to known methods and systems, the presentinvention is distinguished by significantly less technical complexitydespite the requirement of two transcoders.

[0019] Although the present invention has been shown and described withrespect to several preferred embodiments thereof, various changes,omissions and additions to the form and detail thereof, may be madetherein, without departing from the spirit and scope of the invention.

What is claimed is:
 1. A signal transmission and decoding system,comprising: a data source that transmits first encoded data over a firsttransmission medium; a first transcoder that receives said first encodeddata via said first transmission medium, and transcodes said firstencoded data to provide transcoded encoded data that is transmitted overa second transmission medium; a second transcoder that receives saidtranscoded encoded data via said second transmission medium, andtranscodes said transcoded encoded data to provide second encoded datathat is transmitted over a third transmission medium; and a data sinkthat receives said second encoded data via said third transmissionmedium, and decodes said second encoded data to provide decoded data. 2.The signal transmission and decoding system of claim 1, wherein saiddata source comprises a DVD player.
 3. The signal transmission anddecoding system of claim 2, wherein said data sink comprises a DVDdecoder.
 4. The signal transmission and decoding system of claim 1,wherein said data source comprises means for providing said firstencoded data as packetized data that is transmitted over said firsttransmission medium.
 5. The signal transmission and decoding system ofclaim 1, wherein said packetized data comprises a header field and datafield.
 6. The signal transmission and decoding system of claim 1,wherein said first transcoder comprises a phase-locked loop thatconverts the frequency of said first encoded data configured as abiphase signal data, to the frequency of said second transmissionmedium.
 7. The signal transmission and decoding system of claim 6,wherein said first transcoder comprises means for transcoding said firstencoded signal that complies with standard IEC 61937, and transcodedencoded signal is configured and arranged to be transmitted over saidsecond transmission medium that is configured as a MOST network.
 8. Thesignal transmission and decoding system of claim 6, wherein unassignedbits according to standard IEC 61937 are configured to provide commandcontrol data.
 9. The signal transmission and decoding system of claim 8,wherein the unassigned bits are indicative of how many zeroes must beadded to or deleted from the pause packets of the data stream.
 10. Thesignal transmission and decoding system of claim 8, wherein said datasink comprises a multichannel decoder.
 11. The signal transmission anddecoding system of claim 8, wherein said data sink comprises a dtsdecoder.
 12. The signal transmission and decoding system of claim 8,wherein said data sink comprises an MPEG decoder.
 13. The signaltransmission and decoding system of claim 8, wherein said data sinkcomprises an MLP decoder.
 14. A method of transmitting data from a DVDplayer to a DVD decoder, comprising: transmitting encoded data from theDVD player over a first transmission medium; receiving said encoded dataand transcoding said received encoded data to provide transcoded encodeddata; transmitting said transcoded encoded data over a secondtransmission medium; receiving said transcoding encoded data andtranscoding said received transcoded encoded data to provide receivedencoded DVD data; and transmitting said received encoded DVD data over athird transmission medium to the DVD decoder.
 15. The method of claim14, wherein said step of transcoding said received encoded datacomprises transcoding said received encoded data comprising sampled datahaving a sampled frequency f₁, to provide said transcoded encoded datahaving a sampled frequency f₂.
 16. The method of claim 15, wherein saidstep of transcoding said received transcoded encoded data comprisestranscoding said received transcoded data comprising data having asampled frequency f₂ to provide said received encoded DVD data having asampled frequency f₁
 17. The method of claim 16, wherein said secondtransmission medium is configured and arranged as a MOST bus.
 18. Themethod of claim 14, wherein said step of transcoding said receivedencoded data comprises determining the sampling rate f₁, of the datastream supplied by the DVD player and transcoding said received encodeddata to provide said transcoded encoded data having a sampling rate f2associated with the second transmission medium.
 19. The method of claim18, wherein said step of transcoding said received encoded datacomprises changing the number of bits within a pause data field of saidreceived encoded data configured as packetized data.
 20. The method ofclaim 19, wherein said step of changing the number of bits comprisesdeleting a predetermined number of digital zeroes from the pause datafield in order to convert the sampling rate.
 21. The method of claim 19,wherein said step of changing the number of bits comprises adding apredetermined number of digital zeroes to the pause data field in orderto convert the sampling rate.
 22. A motor vehicle signal transmissionand decoding system, comprising: a DVD player that transmits firstencoded data over a first transmission medium: a first transcoder thatreceives said first encoded data via said first transmission medium, andtranscodes said first encoded data to provide transcoded encoded datathat is transmitted over a second transmission medium; a secondtranscoder that receives said transcoded encoded data via said secondtransmission medium, and transcodes said transcoded encoded data toprovide second encoded data that is transmitted over a thirdtransmission medium; and a DVD decoder that receives said second encodeddata via said third transmission medium, and decodes said second encodeddata to provide decoded data.